Hair loss or alopecia, is a common affliction of humans. The most common form of hair loss in both males and females is pattern baldness or androgenic alopecia.
Hair follicles range in size from small, superficial, vellus follicles to large, deep, terminal follicles. The cyclic growth phases of hair follicles are telogen (resting), anagen I-III (developing), anagen IV-VI (growing) and catogen (involuting). Uno, et al., Cyclic Dynamics of Hair Follicles and the Effect of Minoxidil on the Bald Scalps of Stumptailed Macaques, The American Journal of Dermatopathology, 7(3):283-297 (1985).
In the development of androgenic alopecia there is a gradual diminution of follicle size, with conversion of large, terminal follicles producing thick, pigmented hair fibers (terminal hairs) to small, vellus follicles producing fine non-pigmented hair fibers (vellus hairs). In addition, the proportion of growing anagen follicles declines.
It has been found that the compound, 2-(6-cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-4-yl)pyridine-1-oxide stimulates the conversion of vellus hair to terminal hair and increases the growth of terminal hair thereby promoting hair growth.